The present invention relates to a battery-powered towing tractor wherein a floor is formed in the body of the tractor at a position between the front wheels and the rear wheels and a battery is disposed between the floor and the front wheels.
Towing tractor which employs an engine as a drive unit has been used. In such an engine-powered towing tractor, the engine is disposed in the body of the towing tractor at a position that is forward of the operator's compartment and at a level that is higher than the front wheels. In recent years, towing tractor which employs a motor as the drive unit and a battery for driving the motor has been also used. Since the battery of such towing tractor is large in height, width and depth, it is difficult to dispose the battery as in the case of an engine-powered towing tractor. Therefore, the battery of the battery-powered towing tractor is disposed in the tractor body at a position that is forward of the operator's compartment and between the front wheels and the floor.
In a general frame of the above battery-powered towing tractor, a member plate extending in width direction of the tractor body is usually provided between the rear wheels and the floor. Japanese Patent Application Publication No. 2002-331958 discloses such a frame of vehicle body.
Referring to FIG. 5 showing the frame of the vehicle body according to the cited reference, the rear side member 90 (referred to as the rear side rail in the reference) which forms the frame has a front end face 90A which is fixed to the upper part 91A of the suspension bracket 91 (referred to as the suspension support in the reference). The front part 91B of the suspension bracket 91 is fixed to the member plate 92 (referred to as the outrigger in the reference). The suspension bracket 91 supports a rear suspension 93.
A battery-powered towing tractor having a battery in the tractor body at a position that is forward of the operator's compartment and between the front wheels and the floor is larger in the distance between the front wheels and the floor as measured in the longitudinal direction of the tractor body than the engine-powered towing tractor. The distance between the rear wheels and the floor of the battery-powered towing tractor in the longitudinal direction thereof is smaller than that of the engine-powered towing tractor to reduce the wheelbase of the battery-powered towing tractor instead.
In the battery-powered towing tractor, the front and rear wheels receive upward force from the road surface while the body receives the load of the battery. Due to such upward force and battery load, the stress concentrates in the member plate 92 which forms the part of the body between the rear wheels and the floor. However, the member plate 92 which is disposed in a short part in the longitudinal direction of the tractor does not have thickness enough to resist the stress. To reinforce the member plate 92, the frame of the vehicle body disclosed by the reference should be additionally reinforced.
The present invention is directed to a battery-powered towing tractor having a battery disposed between the floor and the front wheels, wherein the member plate is reinforced.